Gut health: Even small increases in cereal fibre beneficial
A first-of-its kind systematic literature review (SLR) of 40 papers, published over the past 20 years, and involving more than 1,300 people in total, showed intact cereal grain fibres increase gut microbiota diversity and/or abundance, with effects apparent from 24 hours to 52 weeks.
The research found even small increases in wheat fibre, as low as 6-8g/day*, were enough to impact the make-up of the gut microbiota. The strongest evidence was found in the role of wheat bran and wholegrain wheat fibre, which demonstrated the most consistent prebiotic effects on gut microbiota composition.
Previous SLRs in this area have largely focussed on supplemented, isolated fibre types (rather than intact cereal grain fibres, like those consumed in everyday foods such as brekkie cereals and bread) or have explored specific conditions, such as irritable bowel syndrome.
The researchers concluded: ‘Increasing cereal fibre consumption should be encouraged for good overall health and for gut microbiota diversity’ and suggest people make simple dietary changes, such as choosing breakfast cereal rich in wheat bran and whole grain wheat or rye breads.
* An average 40g serve of ready-to-eat cereal, muesli or oats contains around 4g of fibre, with some higher-fibre options containing around 13g a serve. When it comes to bread, two slices of wholegrain/wholemeal bread contain an average of 5g of fibre.
Jefferson A, Adolphus K. The effects of intact cereal grain fibers, including wheat bran on the gut microbiota composition of healthy adults: A systematic review. Front Nutr 2019. https://doi.org/10.3389/fnut.2019.00033
Diet and CVD risk: Review of evidence from meta-analyses
A recent review of 16 meta-analyses sheds more light on the links between dietary componentsand the risk of CVD and all-cause mortality – with good news for lovers of grains, nuts and veges!
Among the findings, whole grain brekkie cereals were associated with a 16% reduced risk of CVD (based on two studies which looked at this), and bran a 15% reduced risk (also from two studies). When it came to risk of all-cause mortality, both whole grain brekkie cereals (two studies) and oats/oatmeal (one study) were associated with a 12% reduced risk.
The researchers conclude that nuts, whole grain foods, and certain types of vegetables (such as green leafy vegetables) appear to be beneficial for CVD, while processed meat appears to be harmful.
Some of the food items which showed no association of benefit or harm may actually impact on individual cardiovascular risk factors, such as blood pressure or cholesterol levels, say the researchers. And they highlight that overall diet really is key.
Kwok CS, Gulati M, Michos ED, Potts J, Wu P, Watson L et al. Dietary components and risk of cardiovascular disease and all-cause mortality: A review of evidence from meta-analyses. Eur J Prev Card2019. https://doi.org/10.1177/2047487319843667
Diet and colorectal cancer in UK Biobank: Prospective study
After tracking the diets of nearly half a million UK adults, aged 40-69 years, over an average of almost six years, researchers found those with the highest intake of fibre from breakfast cereals and bread had a 14% lower risk of colorectal cancer (highest fifth of intake, compared with the lowest fifth). The research also found an increased risk for greater red meat and alcohol intake.
In line with the conclusions from another meta-analysis on fibre and colorectal cancer, the researchers state only fibre from cereals, but not fruit and vegetables, was inversely associated with risk.
They say different types of fibre may have different effects on stool transit time and weight – and this may explain the different associations with colorectal cancer. And as intake of fibre from cereals is linked with whole grain intake, phytochemicals or other non-fibre components of whole grains could be responsible for the association, say the researchers.
According to Bowel Cancer Australia, Australia has one of the highest rates of bowel cancer in the world, with more than 15,600 Australians diagnosed with this common type of cancer each year.
Bradbury KE, Murphy N, Key TJ. Diet and colorectal cancer in UK Biobank: A prospective study. Int J Epidemiol 2019. https://doi.org/10.1093/ije/dyz064
Aune D, Chan DS, Lau R et al. Dietary fibre, whole grains, and risk of colorectal cancer: Systematic review and dose-response meta-analysis of prospective studies. BMJ2011. https://doi.org/10.1136/bmj.d6617
Consuming a high-fibre cereal helps gastrointestinal symptoms during Ramadan
A new randomised controlled trial has found eating a high-fibre cereal at dawn during Ramadan is linked with higher satiety rating scores, improved bowel habits, reduced bloating frequency, and improved total and LDL cholesterol.
The researchers randomised 81 study participants, aged 18 to 47 years, to consume either 90g of high-fibre cereal (11g fibre/90g) at dawn (right before fasting) over 20 days, or to maintain their habitual diet intake.
High-fibre cereal consumption resulted in reduced bloating frequency, and improvements in bowel movements – important findings, say the authors, given that constipation is the most frequent gastrointestinal symptom experienced by the end of Ramadan.
Both the control and intervention groups showed a reduction in weight and BMI at the end of the 20-day study period, but there were no significant differences in body weight, percentage body fat, waist circumference and BMI between the two groups.
Jarrar AH, Beasley JM, Ohuma EO et al. Effect of high fiber cereal intake on satiety and gastrointestinal symptoms during Ramadan. Nutrients2019. https://doi.org/10.3390/nu11040939
Of 12 food groups, low whole grain intake found to impact health the most
Suboptimal intakes of 12 major food groups were associated with 45-59% of total disability-adjusted life years from coronary heart disease, stroke, type 2 diabetes and colorectal cancer, across 16 European countries, according to new research.
Of the 12 food groups, a suboptimal intake of whole grains had the biggest impact – followed by nuts, processed meat, fruit, fish, legumes and sugar-sweetened beverages. The researchers say improving intake of whole grains and nuts should be a priority from a public health point-of-view.
This echoes comments from the authors of a major study published this year in The Lancet, which found more than half of diet-related deaths in 2017 were due to the three leading risk factors: high intake of sodium, low intake of whole grains, and low intake of fruits.
The authors of this study concluded: ‘Findings suggest that dietary policies focussing on promoting intake of components of diet for which current intake is less than the optimal level might have a greater effect than policies only targeting sugar and fat’.
Schwingshackl L, Knüppel S, Michels N, Schwedhelm C, Hoffman G, Iqbal K et al. Intake of 12 food groups and disability-adjusted life years from coronary heart disease, stroke, type 2 diabetes, and colorectal cancer in 16 European countries. Eur J Epidemiol2019. https://doi.org/10.1007/s10654-019-00523-4
Diet Collaborators. Health effects of dietary risks in 195 countries, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. The Lancet2019. https://doi.org/10.1016/S0140-6736(19)30041-8Share